A portable test-bench for real-time radiation damage measurements in scintillating and wavelength-shifting fibres

A portable test-bench has been developed to enable the real-time measurement of radiation-induced absorption in scintillating and wavelength-shifting fibres. Such fibres are typically used in the readout of fibre calorimeters or scintillating tiles such as those used in some hadron calorimeters. The testbench has been designed to be used in a range of facilities, such as 60Co irradiators or high-intensity test beam facilities, and can accommodate fibres with length up to 300 mm and diameter greater than 1.0 mm. The test fibres are illuminated using a combined deuterium and halogen light source focussed onto the end of the fibre with a 0.25 NA radiation-tolerant quartz lens. The light transmitted by the fibre is collected by an identical lens and measured as a function of wavelength with a linear charge-coupled device spectrometer covering a wavelength range of 190 to 850 nm. We present the design of the test-bench, and studies of the systematic errors arising from the components. We measured induced absorbance in the fibres tested and determined the major systematic error to be the stability of the light source. Planned enhancements to the test-bench are discussed.